Abstract

The mechanisms and fundamental of low-level light therapy (LLLT), or photobiomodulation are reviewed and compared with that of photodynamic therapy (PDT). However, LLLT combined with PS will enhance the efficacy, where the generation of singlet oxygen via the PS triplet state is more effective. The biomedical applications of LLLT including dermatology and plastic surgery, wound healings, nerve stimulation, dentistry, cancer therapy, and ophthalmic surgeries are reviewed, where lights (lasers or LED) spectra of UV (200-400) um, visible (400-700) nm, near-IR (700-2900) nm, and mid-IR (3-5) um are presented. Two important laws related to the fundamental and efficacy of the photo-biological systems: The Beer-Lambert law (BLL) and the Bunsen-Roscoe law (BRL) of reciprocity are discussed. LLLT efficacy may be improved by combined with photosensitizer-initiated reactive oxygen species (ROS) for light/heat sensitive ion channels.

Keywords: Lasers; Photobiomodulation; Photodynamic therapy; Low level light therapy